1. Field of the Invention
This invention pertains to apparatus for sequencing events typically necessary to launch a missile and, more particularly, to accomplishing this sequencing mechanically, that is, without using electrical components.
2. Description of the Prior Art
Missiles launched from tubes or rails are rigidly attached to such launch apparatus to facilitate transport and handling prior to launch. One type of attachment device presently used requires manual removal whenever launch of the missile is anticipated. To avoid delay in a combat situation, this device can be removed when the missile reaches its launch area, although employing this procedure predisposes the missile to accidents from mishandling prior to launch.
Another commonly used attachment device employs pins which shear upon being subjected to the axial force generated by the thrust of the missile's rocket motor during launch. Although shear pins obviate the need for the manual removal of attachment apparatus prior to launch, they create launch debris and the hazards attendant thereto. When the launch apparatus is held on the shoulder of the operator, the use of shear pins causes reaction forces to be transmitted to the operator, that is, the launch apparatus pulls the operator towards the target, which makes it difficult for the operator to keep the aiming sight positioned on the target.
As a further concession to safety, the warhead fuzes in the current generation of missiles employ two safety locks, the engagement of either of which prevents the warhead fuze from becoming armed. One is a mechanical locking mechanism which is unlocked by the inertial force produced by the axial acceleration occurring during the launch of the missile. The second fuze safety lock is not sensitive to axial acceleration, and is required to be unlocked prior to the launch of the missile. The use of this second safety device is intended to prevent a missile that has been accidentally launched from becoming armed. Such pre-launch safety locks are presently unlocked by an electro-explosive device that is actuated by an electrical signal.
An electrically actuated pyrotechnic device is currently used to ignite the rocket motor milliseconds after the release of the pre-launch safety lock.
Problems with the use of electrical devices to unlock the fuze pre-launch safety lock and ignite the rocket motor arise from their vulnerability to electromagnetic interference as well as degradation from aging and voltage reductions occasioned by low temperature. Electromagnetic interference can be strong enough to induce sufficient current to actuate the electrical rocket motor ignition system, and also to cause the unlocking of the fuze pre-launch safety lock, a confluence of events which could result in the unintentional launching of an armed missle.
With the passage of time, the electrical components in the rocket motor ignition system will degrade, causing an increase in the mathematical probability of a misfire. Even if successfully fired, degradation of the electrical apparatus for unlocking the fuze pre-launch safety lock could result in its failure to operate and thus result in the launching of a missile with an unarmed warhead, with the compound probability of the two foregoing events serving to decrease the reliability of the missile. The problems of rocket motor misfire and failure of the fuze pre-launch safety lock to unlock upon command could similarly be caused by a low voltage output occasioned by cold temperatures.